Opposed twin cylinder engine



1940- c. E. FISHER 2,212,595

OPPOSED TWIN CYLINDER ENGINE Filed March 9, 1936 2 Sheets-Sheet l ii 9 J INVENTOR.

CLHRENCE E. FISHER /wfi' ATTORNEY.

Aug 27, 1940. c. E. FISHER 2,212,595

OPPOSED TWIN CYLINDER ENGINE Filed Mar ch 1936 2 Sheets-Sheet 2 I G04 75 I05 I20 I35 I I I I ZIO 225 240 255 770 285 300 3I5 330345 0 RNGULAR TRAVEL IN DEGREES Fla 5.

INVEN TOR.

ATTORNEY.

Patented 27, 1940 PATENT OFFICE- 2,212,595- orPosEn TWIN" CYLINDERENGINE Clarence E. Fisher, Baltimore, Md.. Application March 9, 1936, Serial No. 67,956,

V 11 Claims. '(ci. 123-53) The present invention relates to internal combustion engines of the twin cylinder type, particularly where the twin cylinders are diametri-- cally disposed with respect to the engine crank shaft.

Twin cylinder internal combustion engines broadly, have been known in the art for a number/of years. They are characterized principally by their flexibility, low fuel consumption, high 10,0verall eiiicien'cy and desirable power-weight ratio. Examples of the known constructions are found in the patents to Hera-1,841,119, issued January 12, 1932, and Kohler, 1,968,524, issued July 31, 1934 in which cases however, the ar- 5 rangement of cylinders is confined to a single row. Such engines have been proposed for two and four cycle operation and the suggested constructions have included sleeve valve and Diesel" types.

This'twin cylinder principle has also been extended to radial engines as exemplified by the patent to Leadbetter et a1., 1,301,141, issued April 22, 1919. This latter construction however, in-

troduces the large frontal area and excessive drag. inherent to all radial engine's.

Another type of engine, employing what is known as opposed cylinders, has also been recognized forits advantageswith respect to smooth and efficient operation, but in practice, the sizes of such engines are restricted by their weight per horse power and by their unsatisfactory heat dissipation. These opposed cylinder engines have been limited, as far as is known, to opposed single cylinders.

In air-craft engines especially, the problems of cooling, high power and economy are con-- tinually increasing with the demands for greater sizes, speeds and cruising areas.

By the present invention, the various advan- 40 tages of the twin cylinder engine and the opposed cylinder engine are combined to produce what may be called an-opposed twin cylinder engine. Perhaps the nearest approach to such a construction in the prior art will be found in the Leadbetter patent already referred to, the

chief disadvantages of which, especially for air-' craft have already been alluded to. An engine of the opposed twin cylinder type on the other hand, readily adapts itself to' horizontal installation in an airplane wing between the front and rear spar, for example," whereupon all undue drag is eliminated.

Some of the features contributing to the lower weight per horse power and increased operating 5 efficiency ofanengine of the present construction, are the need for but a single crank shaft, the adequacy of a small crankcase, the requirement of but one'spark plug (in engines using electric ignition) per cylinder, the requirement of a smaller volume of cooling :liquid (where. 6 liquid cooling is employed) "due to the substantial I-shape of the engine, the possibility of using thin finned cylinder barrels, and a connecting rod arrangement whereby fewer main connecting rods are necessary, and accordingly, a re- 10 duced number of bearing caps will be required. The object of this invention is, therefore, to produce an engine of the opposedtwin cylinder type wherein one or more units, each comprising four cylinders, has its cylinders arranged in pairs, which pairs are symmetrically disposed withrespect to the engine crank shaft in such a way that a line passing through the crank shaft axis and the center line of the one pair of cylinders, is coincident with thecenter line of the go other pair of cylinders. Each pair of cylinders is preferablyprovided with a common combustion chamber and common ignition means.- The pistons in each cylinder of the four comprising a unit are operatively connected with the crank 25 shaft, and preferably to a' single crank pin on the crank shaft, so that each unit of four cylinders will comprise a master connecting rod to and succeeding units.

In the accompanying drawings: Fig; l is a sectional elevation of one embodiment of the present invention; V Fig. 2 is a longitudinal section, partially broken, taken along line A--A of Fig. 1;

" Fig. 3 is a sectional plan view taken along line 40 BB of Fig. 1;

Fig. .4 is a diagrammatic view of an engine unit; and i Fig. 5 depicts by curves the relative travel of the pistons of an engine unit. 45

An engine unitcomposed of four cylinders, or two twin cylinders, is shown in Fig. 1 of the drawings, and in Fig. 2, two such units are shown in banked relation. In some instances a complete engine might be defined by the number of 50 cylinder block containing at least one twin oylinder 9, the two cylinders constituting a, twin.cylinder preferably having their axes parallel. A division wall lll separates the cylinders of one unit from those of an adjacent unit, the number of such adjacent units in banked relationship depending upon the desired horse power. As shown, a cylinder head ll common to thetwo cylinders constituting a pairprovides a common combustion chamber and in this particular form, it is integral with the cylinder block. Cooling jackets are provided in the head and block defining a passage l2 for the circulation of cooling liquid, which passage extends between the two cylinders of a pair. I

Two intake valves [3 and two exhaust valves M are provided for each pair of cylinders, and

their arrangement as shown in Fig. 3, is preferwill be noted that the exhaust ports IE are located.

with respect to the cylinders so as to deliver the exhaust gases to the outside air through the shortest possible path and consequently. with least resistance. The intake ports 17 are arranged so as to deliver the combustible charge towards the center of each cylinder in such a manner that the cooling characteristic of the head will be greatly enhanced.

Each cylinder is provided with a piston 8 for cooperation with a crank shaft'passing through the crank case and carrying a suitable number of crank pins 19, one for each unit. One piston of each unit of four cylinders is provided with a master connecting rod which cooperates with a bearing cap 20 and bearing 21' for assembly on the crank pin iii. The three remaining pistons of each'unit are provided with connecting rods 2, 3 and t which are articulated to the master connecting rod assembly by suitable link pins 6.

The cylinder head common to each pair of cylinflame travel across the pistons of a pair of cylinders in a direction corresponding to the rotational direction of the crank shaft.

crank shaft, while arrows 23 indicate the direction of flame travel from the spark plug across the cylinders. 1

, It will be noted with respect to Fig. 4 that the paths of the link pins 6 approach ellipses. This figure depicts the pistons as A, B, C and D for the purpose of representing their relative travel in the curves of Fig. 5. The consequent motion serves to increase the piston speed during the firing stroke and yield a higher heat eificiency. Another effect is an increase in time for intake and exhaust with a resultant increase in volu metric efficiency.

In an engine built up of a, series of these units,

alternate units will preferably have the r master .connecting rods diagonally disposed for the pur- An arrow in. Fig. 1 clearly depicts a clockwise rotation of the has been shown and described, it will serve adequately as an example of the present invention.-

The appended claims are intended to cover all equivalents as would be suggested to a worker in the art. I

I claim: I i

1. An engine of the twin cylinder type comprising a crank shaft and plurality of units, each of said units having four cylinders arranged in pairs, the cylinders of each pair having parallel axes which are coincident with the axes of the cylinders of the other pair, a piston in each cylinder, a master connecting rod connecting one piston of each unitwitha pin on said crank shaft, the remaining pistons having connecting rods articulated to said master connecting rod, alternate units having their master connecting rods diametrically disposed.

2. A unit for an engine of the twin cylinder type comprising two pairs of cylinders disposed at 180 with respect to a crank shaft, pistons in said cylinders operating upon a single crank on the crank shaft, the cylinders of each pair having a common combustion chamber, the igniting means for each pair of cylinders being so disposed that upon ignition, the direction of flame travel corresponds to the direction of rotation of.

said crank shaft.

3. A balanced engine of the twin cylinder type composed of a plurality of four-cylinder units, each unit comprising a crank shaft having a pin and two pairs-o1 twin cylinders disposed about at V said crank shaft at to one another, each pair of cylinders having a common combustion cham-' ber, pistons in said cylinders, a master connectingrod connecting one of said pistons to said crank pin, the remaining pistons having connecting rods which are articulated to said master connecting rod, the axes of the individual cylinders lying in a single plane perpendicular to the crank shaft axis, the cylinders of adjacent units being aligned longitudinally of the crank shaft and certain of said units having their master connecting rods in relatively staggered enginebalancing relationship.

4. A balanced engine of the twin cylinder type composed of a plurality of four-cylinder units, each unit comprising a crank shaft having a pin, two pairs of twin cylinders symmetrically dis- .posed with respect to said crank shaft, the twin cylinders each comprising'two cylinders having a common combustion chamber and arranged in a plane perpendicular to the axis of the crank shaft, pistons in said cylinders, a master connecting rod articulating one of said pistons to the crank pin and connecting rods articulating the other pistons to said master connecting rod, the

cylindersof adjacent units being aligned longitudinally of the crank shaftand certain of said units having their master connecting rods in relatively staggered engine-balancing relation-' ship.

5. A balanced engine of thetwin cylinder type composed of a plurality of four-cylinder units,

each unit-comprising a crank shaft having a 6 crank pin and two pairs of substantially parallel cylinders diametrically, disposed with respect to the axis of the crank shaft, each pair having a said cylinders lying on a single plane transverse to said crank shaft, each cylinder having a piston, and each piston having a separately articulated connecting rod operatively connected! to said crank pin, one of saidconnecting rods being directly connected to said crank pin, the other common combustion chamber, the axes of all of connecting rods being articulated to the first,

the cylinders of adjacent units being aligned longitudinally of the crank shaft and certain of said units having their master connecting rods in relatively staggered engine-balancing relationship.

6. A substantially flat balanced engine of the twin cylinder type composed of a plurality of four-cylinder units, each unit comprising a crank shaft having a pin and four co-planar cylinders arranged in substantially parallel pairs on oppocrank shaft, each pair having a common combustion chamber, said cylinders containing pistons operatively connected through connecting rods to said pin, the axes of one pair of said cylinders corresponding with the axes of the other pair of cylinders respectively, said axes being symmetrical with respect to said'crank disposed,,the cy shaft and lying in a plane transverse to said crank shaft, one of said connecting rods being directly connected to said pin, the other of said connecting rods being connected to the first, the cylinders of adjacent units being aligned longitudinally of the crank shaft and certain of said units having their master connecting rods in relatively staggered engine-balancing relationship.

"7. A substantially flat balanced engine of the twin cylinder type composed of a plurality of' four-cylinder units, each unit comprising two pairs of cylinders symmetrically disposed at 180 with respect to a crank shaft, pistons in said cylinders operating upon a single crank on the crank shaft, the cylinders of each pair having a common combustion chamber,

said cylinders lying in a single plane transverse to said crank shaft, a. master connecting rod connecting one of said pistons to said crank, and articulating rods connecting pistons to said master rod, the cylinders. of ad'- jacent unts being aligned longitudinally of the crank shaft and certain of said units having their master connecting rods in relatively staggered engine-balancing relationship.

8. A balanced engine of the twin cylinder typecomposed of a purality of four-cylinder units,

each unit comprising a crank shaft with respect to which two pairs of cylinders are diametrically 'nders of each pair bein in communication, a p ton carried by each cylinder, and connecting rodsassociating said pistons through articulated joints to said crank shaft, the axes of all of said cylinders lying in a single plane transverse to said crank shaft, one of said connecting 55 rods being directly connected to said crank shaft,

shi

the axes of all of the remaining having a crankpin,

the other of said connecting rods being connected tothe first, the cylinders of adjacent units being aligned longitudinally of the crank shaft and certain of said units having their master connecting rods in relatively staggered enginebalancing relationship.- 1 v 9. A substantially flat balanced engine. of the twin cylinder type composed of. a plurality of four-cylinder units, each unit comprising a crank shaft with respect to which two pairs of cylinders are symmetrically disposed, the cylinders of each pair having a common combustion chamber, the center line through one pair of cylinders being coincident with the center line of the other pair of cylinders, a piston in each cylinder, a master connecting rod connecting one of said pistons to said crank shaft and connecting rods associating said units having their master connecting rods in relatively staggered engine-balancing relation- 10. A balanced engine of the twin cylinder type composed of a plurality of four-cylinder units, each unit comprising a crankcase, a crankshaft having a crankpin, parallel interconnected cylinders having acommon combustion chamber disposed on diametrically. opposite sidesv of the crankcase, pistons in each of the cylinders, a master connecting rod interconnecting one of said pistons and the crankpin, and a plurality of articulated connecting rods interconnecting the other pistons and said master rod, the cylinders of adjacent units'being aligned longitudinally of the crank shaftand certain of said units having their master connecting rods in relatively staggered engine-balancing relationship.

11. A balanced engine" of the twin cylinder type composed of a plurality of four-cylinder units, each unit comprising a crankcase, a crankshaft parallel interconnected cylinders having a common combustion chamber disposed on opposite sidesof in each of the cylinders, a master connecting rod inchiding'a bridge rocker interconnecting one of the pistons and the crankpin,- and a plurality of articulated connecting rods interconnecting the other pistons and the bridge rocker, the cylinders of adjacent units being aligned longitudinally of v the crank shaft and certain of said units having their master connecting rods in relatively staggered engine-balancing relationship. CLARENCE E. FISHER.

the crankcase, pistons 

